Utilities::getTempDir: Make sure that the temporary directory is owned by the current user.
Utilities::getTempDir: Make sure that the temporary directory is owned by the current user.

This fixes a potential situation where another user creates the
temporary before simpleSAMLphp attempts to create it. Anther user
creating the directory could make simpleSAMLphp overwrite arbitrary
files on the system.

cb8/saml2,ArtemTeleshev/php-saml2,sgomez/saml2,newmen/saml2,sitya/saml2,simplesamlphp/saml2,madmatt/saml2